KMP刷题记录

【BZOJ4698】[SDOI2008]Sandy的卡片

• 差分一下然后选一个串，用这个串的所有前缀和其他串kmp，求出最长的公共部分即可
• 代码：

   #include <bits/stdc++.h>
   #define f(c,a,b) for (int c=a; c<=b; c++)
   #define nmax 1010
  
   using namespace std;
   int n;
   int a[nmax][nmax];
   int b[nmax], nex[nmax], l[nmax];
  
   void buildnext(int lb){
       nex[] = -;
       nex[] = ;
       f(i,,lb){
           int j = nex[i-];
           for(;b[j+]!=b[i]&&j>=; j=nex[j]);
           nex[i] = j+;
       }
   }
  
   int kmp(int lb, int id){
       int ans=;
       int j=;
       f(i,,l[id]){
           for(;b[j+]!=a[id][i]&&j>=; j=nex[j]);
           j++;
           ans = max(j,ans);
       }
       return ans;
   }
  
   int main(){
       int ans=;
       cin >> n;
       f(i,,n){
           scanf("%d", &l[i]);
           f(j,,l[i]) scanf("%d", &a[i][j]);
           f(j,,l[i]) a[i][j-]=a[i][j]-a[i][j-];
           l[i]--;
       }
       f(i,,l[]){
           int c=;
           f(j,i,l[]) b[++c]=a[][j];
           buildnext(c);
           int ta=nmax;
           f(j,,n) ta = min( kmp(c,j), ta );
           ans = max(ans, ta);
       }
       printf("%d\n",ans+);
       return ;
   }